It was a bit bizarre Seldon took a knee after seemingly being hit in the left eye, he went down in the fifth but I was not sure Johnson hit him with a really hard shot. I think Seldon had convinced himself he could do it after getting down to 221lbs, by the fifth he realised that Johnson was just too much. Johnson was impressive to a certain extent but he needs to step it up. Beating Terry Smith and an 41yr old Seldon do not make you a top heavyweight, he needs to be matched a bit tougher than that.
It takes time...you can't rush a fighter too fast...he is still learning, honing his skills and finding out what he can and can't do/get away with. He will gradually step up and I think he will fare well against anyone in years to come...If he perfects his style he can be trouble for anyone...